THEORY of the EARTH. 283 



cles of lava, that is to fay, in our whinftone, every fpecies of 

 mineral appearance is occafionally to be found. Let thofe who 

 have the opportunity to examine, fay, what are to be found in 

 proper lavas, that is, thofe of the erupted kind. Sir WILLIAM 

 HAMILTON informed me, when I mewed him thofe mineral 

 veins and fpars in our whinftone, that he had never obferved 

 the like in lavas. 



WE have now formed fome conclufions with regard to the 

 nature and production of thofe parts of the land of this globe 

 which we have had the means of examining perfectly ; but 

 from the accounts of travellers, and from the fpecimens which 

 are brought to us from diftant parts, we have reafon to believe, 

 that all the reft of the earth is of the fame nature with that 

 which has been now confidered. The great mafles of the earth 

 are the fame every where ; and all the different fpecies of earths, 

 of rocks or ftone, which have as yet appeared, are to be found 

 in the little fpace of this our ifland. 



IT is true, that there are peculiar productions in the mineral 

 kingdom which are rare, as being found only in few places j 

 but thefe things are merely accidental in relation to the land, 

 for they belong in property to thofe parts of the mineral region 

 which we never fee. Such are, the diamond of the eaft, the 

 platina of the weft, and the tin of Cornwall, Germany, and 

 Sumatra. Gold and filver, though found in many countries, 

 do not appear to be immediately neceflary in the production of 

 a habitable country. Iron, again, is univerfal in the operations 

 of the globe, and is found often in that profufion which equals 

 its utility. Between thefe two extremes, we find all other mi- 

 nerals, that is to fay, here and there in moderate quantity, and 

 apparently in fome proportion to their ufe. But all thefe fub- 

 ftances are to be confidered as the vapours of the mineral re- 

 gions, condenfed occafionally in the crevices of the land ; and 

 it is only the rocks and ftrata (in which thofe mineral veins are 

 found) that are now examined with regard to their original 



N n 2 compofition 



